Generally, a bicycle includes front and rear wheels before and after a bicycle frame, and a pair of pedals as a power supply source between two wheels. The driving force for bicycle is obtained through pedaling and then the force is transmitted to the rear wheel via a driving sprocket, a chain and a driven sprocket. This general bicycle travels forward when pedaling forward by a rider and the rear wheel of the bicycle rotates without load by an one-directional ratchet of a hub of the rear wheel when pedaling rearward, wherein the rotation of the rear wheel without load is called "idling".
Also, inventions for new parts of bicycle which can allow of bi-directional pedaling to the general bicycle to which only one-directional pedaling is allowed have been disclosed. Particularly, those of Mantzoursos et al. and Foster et al. will be introduced as follows.
According to the invention of Mantzoutsos et al. (EPO Publication No. 0,369,925), two gears are installed on a pedal shaft and an auxiliary gear is installed between two gears to be detachable. Here, the bicycle of this invention can travel like a general bicycle when pedaling in the state where the auxiliary gear is detached. However, the bicycle can travel forward through the change of rotation direction of the pedal shaft by the auxiliary gear when pedaling rearward while the auxiliary gear is attached.
On the other hand, according to the invention of Forster et al. (U.S. Pat. No. 5,435,583), a gear box is installed on a pedal shaft, including two gears, two clutches therebetween and a bevel gear between two gears' teeth. Here, the bicycle of this invention can travel like a general bicycle when pedaling while the clutch is coupled with the right gear. However, the bicycle can travel forward through the change of the rotation direction of the pedal shaft by the bevel gear when pedaling rearward while the clutch is coupled with the left gear.
The above two inventions are meaningful in the aspect of the bi-directional pedaling apparatus which can drive the bicycle forward by adopting a mid gear when pedaling rearward. However, life span of the bi-directional pedaling apparatus is shortened due to abrasion of a specific portion to which a force required for changing the power direction is applied and there is inconvenience in the operation of the apparatus for changing power direction.
A bi-directional pedaling apparatus obtained by solving the above defects is disclosed in Korean Patent Application No. 94-13391. According to this application, a predetermined closed space is formed between one end of a pedal shaft and a driving sprocket, and two one-directional ratchets are installed at the outer and inner portions of the space. Also, a ratchet wheel to which a plurality planetary gears are rotatably set, and a changing lever for controlling the locking and unlocking of the outer one-directional ratchet are provided in the closed space. The bi-directional pedaling mechanism of the bicycle in the bi-diredtional pedaling apparatus is as follows.
When pedaling forward, the pedal, the ratchet wheel and the driving sprocket integrally rotate to travel the bicycle forward. Meanwhile, the outer one-directional ratchet instead of the inner one-directional ratchet functions by the changing lever when pedaling rearward. Here, there are two cases where the outer ratchet is locked and unlocked. First, when pedaling rearward while the outer ratchet is locked, the plurality of planetary gears rotate around own shafts thereof, so that the rotation direction of the pedal shaft is changed and then power from the pedal shaft is transmitted to the driving sprocket, thereby driving the bicycle forward. Second, when pedaling rearward while the outer ratchet is unlocked, the planetary gears rotate and simultaneously revolve around the pedal shaft in cooperation with the ratchet wheel. As a result, power from the pedal shaft cannot be transmitted to the driving sprocket, resulting in the idling of the pedal.
According to the above-described Korean Patent Application No. 94-13391, the concentration of force on a specific portion by the changing of power direction is prevented by dispersing the force using the plurality of planetary gears. Thus, life span of the bi-directional pedaling apparatus is prolonged and the rotation direction of the pedal shaft can be simply changed by using the changing lever. Also, the bi-directional pedaling apparatus can operate actively by adopting small and precise parts.
However, in the above-described Korean Patent Application No. 94-13391, mass production of the parts and assembling of each part are difficult and the bi-directional pedaling apparatus cannot be attached directly to a conventional bicycle, so that the parts thereof should be improved partially. Also, each constituent part may be broken by a reverse-load caused when pulling back the bicycle.